1. Technical Field
The invention relates to disposable hypodermics, particularly to safety catheters with retractable needles.
2. Related Art
A conventional intravenous catheter set is composed of a needle, a catheter and a needle cap. The catheter is passed through by the needle and the needle cap covers the needle and catheter. The user first uncovers the needle cap before inserting the tip of needle along with the catheter into a patient's skin. Then, the user extracted the needle by abutting the catheter against the patent's skin, leaving the catheter indwelled in place of the patient's skin. The needle is a disposable piece. A used needle is very dangerous and infectious and must be carefully cloaked by the cap. Although a kind of safety catheter containing a pre-established vacuum has appeared in the market, it needs to maintain the pre-established vacuum before the use, otherwise its safety mechanism will not be workable. Adversely, an unworkable safety catheter is more dangerous than an intravenous catheter without a safety mechanism because users are more likely to be injured if the safety catheter is not being workable.